1. Field of the Invention
This invention relates to the packaging semiconductor components and, more particularly, to the packaging of semiconductor components which require a large number of electrical connections to external devices. The requirement of a large number of connections to a semiconductor component which is physically small can exceed the parameters imposed on the conducting leads of the leadframe.
2. Description of the Related Art
Many modern electronic systems incorporate various modular electronic components. For example, personal computers may comprise modular electronic components in the form of Dynamic Random Access Memory units. Each of the modular electronic components may comprise an integrated circuit fabricated on a semiconductor substrate. Each modular electronic component is coupled to the electronic system by a series of pins extending in a predetermined sequence from a body of the modular electronic component. The pins are coupled to leads of a lead frame. The lead frame is coupled to the integrated circuit during the fabrication of the modular electronic component.
A specific electronic signal may be associated with each pin of the modular electronic component. When the modular electronic component is properly coupled to the electronic system, the pins transmit these electronic signals between the integrated circuit and corresponding lines of the electronic system. Thereby, the electronic system may function properly. If, however, the sequence of pins of the modular electronic component does not match a sequence of corresponding lines of the electronic system, the electronic system will not receive the proper signals at the proper lines. Therefore, the electronic system would not function properly.
One typical method for connecting the lead frame to the integrated circuit is referred to in the industry as leadframe-over-chip (LOC) technology. As mentioned above, the integrated circuit is typically fabricated on a semiconductor substrate. The integrated circuit and substrate is commonly known as an "integrated circuit chip." The integrated circuit also comprises a row of bonding pads for connecting the integrated circuit to the leads of the lead frame. According to LOC technology, the lead frame is placed over the integrated circuit chip such that the row of bonding pads may be coupled to appropriate leads of the lead frame.
Typically, the leads of a lead frame are routed in only 2 dimensions. This spacial limitation means that leads may not cross over other leads. Consequently, the sequence of leads in a lead frame will be the same as the sequence of the bonding pads on the integrated circuit. Integrated circuits are manufactured by a number of different companies. Often, each of these companies produce competing integrated circuits that perform the same function. However, the various integrated circuits differ in the manner in which the integrated circuits are organized on the semiconductor substrate. For example, because integrated circuits are complicated and designed independently by these companies, the sequence of bonding pads may vary from manufacturer to manufacturer even though the integrated circuits perform the same function. Therefore, each modular component produced by a particular manufacturer may have a different "pin out." A "pin out" is the physical sequence in which pins associated with specific electronic signals extend from the modular electronic component.
Two modular components that perform the same function but have different pin outs will not both function properly when coupled to a specific electronic system. At least one of the modular components will not provide the appropriate electronic signals to the system. This is contrary to the interchangability that modular components should provide. A prior solution involves adding a few semiconductor processing operations to change the sequence of bonding pads of an existing integrated circuit design. In this manner, the bonding pads may be formed in the same sequence as the leads of the lead frame.
For several years, the number of the electronic components and the complexity of the electronic components associated with each integrated circuit has continually increased without a commensurate increase in the size of the integrated circuit itself. As a consequence of the increased number and complexity of the integrated circuit, an increasing number of electrical connections must be made to the integrated circuit. Because the routing of the electrical connection must typically be made in two dimensions, only limited selection of the position of bonding pads is available. In addition, the apparatus performing the bonding of the conducting wires to the leadframe and to the bonding pads on the integrated circuit has physical limitation with respect to the size of the leads on the lead frame, the traditional approach to coupling the bonding pads to the leadframe has become inadequate.
A need has therefore been felt for apparatus and a method for electrically coupling the greater number of bonding pads of a semiconductor integrated circuit component to a leadframe in the leadframe-over-chip technology while observing the physical limitations required for a satisfactory bonding process and the limitation imposed on the routing of leads in integrated circuits.